Automatic drilling-machine



E. J. KINGSBURY.

AUTOMATIC DRILLING MACHINE.

APPLICATION FILED MAY 5, I919.

Patented. May .31, 1921.

6 SHEETS'SHEET Q W) wv'ewtoz E. I. KINGSBURY.

AUTOMATIC DRILLING MACHINE.

APPLICATION FILED MAY 5, 1919.

awvamtoz Patented. May 31, 1921.

e SHEETSSHEET 2- E. I. KINGSBURY.

AUTOMATIC DRILLING MACHINE.

APPLICATION FILED IIIAY 5. I919.

1,379,765. ent May 31, 1921.

6 SHEETS-SHEET 1 E. J. KINGSBURY.

AUTOMATIC DRILLING MACHINE.

APPLICATION FILED MAY 5. 1919.

1 379765. Patented May 31, 1921.

6 SHEETS-SHEET 5.

WWW

E. J. KINGSBURY. AUTOMATIC DRILLING MACHINE.

APPLICATION FILED MAY 5. 1919.

1,379,765. Patented Mayisl, 19211.

6 SHEETS-SHEET 6.

PTENT AUTOMATIC DRILLING-MACHINE.

Specification of Letters Patent.

Patented May 31, 1921.

Application filed May 5, 1918. Serial No. 294,891.

To all whom it may concern:

Be it known that I, EDWARD J. KINGS- BURY, a citizen of the United States, residlng at Keene, in the county of Cheshire, State of New Hampshire, have invented certain new and useful Improvements in Automatic Drilling-Machines, of which the following is a description, reference being had to the accompanying drawing and to the figures of reference marked thereon.

My invention relates to new and useful improvements in automatic drilling machines.

An object of the invention is to provide a drilling machine of this character, in which a predetermined positive feed of the drill spindle is dispensed with and a weight or spring is used to impart the forward thrust to the drill spindle, and means is provided for adjusting the tension of the weightv or spring, in accordance with the strength of the drill and the character of the work upon which it is operating.

Another object of the invention is to maintain an even and steady pressure 011 the drill under normal working conditions and prevent a rapid forward feed of the drill spindle when the drill enters a soft spot or breaks through the bottom of the hole in the work, as well as providing an automatic means to stop the feeding forward of the drill spindle when the drill becomes dull and is not cutting efficiently after it has completed its drilling operation and re turned to its starting point.

A further object of the invention is to provide a machine in which the drill is automatically returned to its starting point after it has broken through the work on which it is operating, and the returning means being the maximum forward feed governing means.

A still further object of the invention is to provide a machine of the above character view taken on the line 4-4 of Fig. 2, and looking in the direction of the arrow;

Fig. 5 is a horizontal sectional view taken on the line 5-5 of Fig. 2 looking clownwardly and showing the worm gear out of mesh with the worm carried by the continuously operated shaft;

Fig. 6 is a diagrammatic view, showing the normal position of the worm gear and the latch held in engagement with the sleeve carried thereby;

Fig. 7 is a similar view, showing the latch being thrown out by engagement of the pin carried by the sleeve;

Fig. 8 is a similar view, but showing the lug carried by the latch in engagement with the lever for stopping the feed of the drill spindle.

Referring now to the drawings, 1 represents the base which, as shown, is of an elongated form having feet 2 provided with openings, whereby the same may be tightly bolted upon the desired form of support. One end of the base is provided with an upwardly extending curved arm 8, which is provided at its upper end with a cylindrical enlarged portion a, forming a bearing for the drill spindle 5. The said arm below the bearing 4, is provided with an upwardly and forwardly extending arm 6, which has an enlarged vertically disposed plate 7 having openings, so that a work support of any character may be bolted thereto for supporting the work being operated upon by the drill carried by the drill spindle 5. The opposite end of the base is provided with an upwardly and rearwardly extending arm 8, having a cylindrical enlarged portion 9 which forms a bearing for the opposite end of the drill spindle 5, whereby said drill spindle may be moved longitudinally, as will be hereinafter more fully described.

Carried by the drill spindle 5 is a belt pulley 10 of an elongated form, to hold the belt from the motor, and by means of which the drill spindle is rotated, as later described. Carried by the hub 11 of the pulley 10, is a bushing having a peripheral groove, in which is loosely mounted a ring 12, carrying on opposite sides horizontally arranged pins. Pivotally mounted upon said pins is the forked end 18 of the arm 14:, which has a slot 15 therein, through which passes a set screw 16 and by means of which the drill spindle is connected to the feeding and returning means, later described. The outer end'of the arm is bent upwardly, as indicated at 17, which forms the handle portion 18, spaced a sufiicient distance from the bearing 4 to enable it to be gripped for ad justing the drill spindle 5, either forwardly or backwardly, independent of the operating means when the set screw 16 is released. This arrangement of the arm 14 allows the drill spindle to freely rotate independently of the arm and yet through said arm the spindle is fed forward. By the adjustable connection of the set screw 16 with the block 37, the drill spindle can be moved forward to bring the drill into contact or close prox imity with the work, so that when the machine is started the drill will also immediately start cutting.

. .Carried by the base 1 of the machine on one side are two longitudinally arranged bearings 19 and 20, in which is rotatably mounted the elongated shaft 21, having its free end terminating at a transverse point about midway the length of the pulley 10. Carried by the rear end of the shaft 21 is a pulley 22, around which passes the crossed belt 23, which also passes around the pulley 10, whereby the shaft 21 is continuously rotated with the rotation of the pulley 10. The shaft 21, adjacent the bearing 19, is provided with a worm 24 meshing with a wormgear 25, mounted upon the transverse shaft 26. This shaft 26, as shown, extends transversely of the base 1, and is mounted in the bearings 27 and 28 carried by the base.

The bearings 27 and 28, as shown in Fig. 5 of the drawings, are spaced some distance apart exposing a portion of the shaft. This portion of the shaft 26, between the bearings 27 and28, is provided with a friction drum 29 adapted to engage the periphery of the eccentric 30, so that during the forward movement of the drill spindle the rapidity is controlled by the eccentric 30 bearing on the friction drum 29, but only when there is little or no resistance to the forward movement of the spindle. When there is a resistance to this forward movement, as when work is being drilled, the thrust is taken almost wholly off the eccentric against the drum, so that the eccentric slips on the drum. There is just enough friction between the eccentric'and drum to keep them always in contact as the drill spindle works its way forward. The slipping is continuous until the drill has overcome all resistance, as when it breaks through the work. The full thrust of the spring is then taken up by the eccen tric against the drum, thereby increasing the friction so that the eccentric rotates at the predetermined speed of the drum. The

ing arm '34 of the standard .3 below the drill V spindle 5. The upper ends of the levers 31 and 32 are provided with a series of openings 35, through which pass screws 36, which also pass intothe block 37, and are adj ustably connected to the arm 14 by means of the set screw 16, so that the drill spindle 5 may be adjusted forwardly to bring the'drill in contact with the work independent of the feeding levers. The series of openings allow the levers to be attached to the block 37 at any of the three openings, so that the fulcrum of the'levers is changed and the feed of the drill spindle increased or decreased, as desired, and aswill be readily seen by referenceto Fig. 2. I

The levers 31 and 32 have pivotally connected thereto above-their lower ends, as at 38, an upwardly curved yoke 39, which has its rear end provided with an eye 40, to which is connected, orin which is inserted the hooked end 41 of the spring 42. This spring 42 is provided at its opposite end with a hook 43 which hooks into the eye 44, carried by the bolt 45. This bolt 45, as shown, extends through the upwardly extending arm 8 and has a thumb nut 46 screwed thereon, whereby the tension of the spring 42 on the levers 31 and 32 may be increased or decreased, to increase or de-' crease the spring feed of the spindle, according to the character of the work upon which the drill is operating. Pivotally mounted between the lower ends of the levers 31 and 32 is the eccentric 30 which normally bears against the drum 29 and upon the rotation of the drum 29 the eccentric will rotate therewith. The periphery of the drum is provided with a series of'grooves 47, into which extend the ringlike projections 48 carried by the eccentrics, whereby a greater frictional contact between the drum and the eccentric is obtained. ing carried by the levers 31 and 32 is drawn against the drum by the tension of the spring 42, all of which will be later more fully described in the complete operation of the machine.

The shaft 26, beyond the bearing 28, is provided with a worm 49, which meshes with the worm gear 50. The worm gear 50 is rotatably mounted upon theupper end of the member 51, carried by the outer end of the oscillating shaft 52, which is mounted in the lower end of the base 1 and extends entirely therethrough. The opposite end of the shaft 52 is provided with an upwardly extending arm 53, having a sprlng 54 connected thereto and normally holds the said arm in a. rearward position. Connected to this arm 53 is a link 55 which is connected to a lever 56 intermediate its ends. The said lever 56 ispivoted at 57 to the "frame and extends upwardly and has connected thereto an operating rod 58, whereby the shaft 52 The eccentric 30 beis oscillated for throwing the worm gear out of engagement with the worm 49, for the purpose hereinafter more fully described.

The eccentric 30 is provided at one side. with a cam-shaped member 59 adapted to engage the roller 60, carried by the inner side of the lever 56 and whereby said lever is oscillated during each revolution of the eccentric 80 for throwing the worm gear 50 out of engagement with the worm 4 9, for

the purpose hereinafter described. The worm gear 50 is loosely mounted upon the member 51 to freely rotate thereon and a spring 61 has its upper end secured in the slot 62 in the member 51, and its opposite end secured to the worm gear 50, whereby the spring is wound upon the rotation of the worm gear, so that, by the rocking of the member 51 to throw the worm gear 50 out of engagement with the worm 49, the worm gear is rotated and returned to its normal position, as hereinafter more fully described. V

The gear 50 is provided with an integral downwardly extending sleeve 63 which rests on a collar 64 carried by the member 51, so that the downward movement of the sleeve is limited. This sleeve, above its lower end, is provided with a collar 65, forming a circumferential groove 66 between the collars 64 and 65, and between which extends the outwardly turned ends 67 of the catch 68. The catch 68 is'of an elongated form and is pivoted intermediate its ends at 69 to the base so that it can swing vertically and sidewise by having the opening larger than the pivot 69, as shown in dotted lines in Fig. 3. The said catch is provided at its outer end with a weight 70 which normally tends to throw the hooked or outwardly turned end 67 upward, the purpose of which will be later described. Thepivot 69 has a leaf spring 69 surrounding it and extends forwardlyand' engages the outer face of the catch and holds the same inwardly toward the member 3 of the base and holds the hooked end 67 in the circumferential groove 66, and thus holds the rear end of the catch downwardly against the tension of the weight 70. This catch 68, on its inner edge, is provided with an inwardly extending lug 71 adapted to catch in the notch 72, in the lower end of the lever 31, whereby the rear ward movement of the lever is permitted to stop the feed of the drill inthe event it is not efficiently cutting.

The sleeve 63 is provided with a pin 7 3, and is normally held in engagement with a pin 74 carried by the collar 64. The spring 61 normally holds the pin 73 agalnst the pin 74 and upon the rotation of the worm gear 50 by the worm 49, the pin 73 engages the hooked end 67 of the catch 68 and forces the same inwardly from between the collars 64 and and the weight throws the rear end of the lever upwardly in the path of travel of the lever 31 and the lug 71 catches in the notch and the rear movement of the lever is arrested and the feed of the drill stopped.

The operation of the machine is as follows: The pulley 10 is continuously rotated by a belt from an electric motor, or the like, not shown, which in turn rotates the drill spindle 5 and the drill carried by the drill chuck 75. The pulley 10 is keyed to the drill spindle against rotation and longitudinal movement and is connected to the levers 31 and 32 by the member 15, as heretofore described. The levers 31 and 32 are intermediately pivoted and their upper ends fed forward by the spring 42 as the drill works its way through the work supported by the plate 7, not shown. The drill spindle in its forward movement is retarded by the work being operated upon and the cam 30 carried by the lower end of the lever takes some of the pressure of the spring from the levers and, therefore, the entire strength of the spring is not brought to bear on the drill spindle. The belt 23 is continuously driven by the pulley 10, which in turn continuously rotates the pulley 22 carried by the shaft 21. The rotation of the worm 24 by the shaft continuously rotates the transverse shaft 26 through the worm gear 25. The drum 29 carried by the shaft is continuously rotated, which, being in frictional contact with the eccentric 30, rotates the same and allows an even constant predetermined forward feed of the drill'spindle. This forward movement of the drill spindle is governed by the rim speed of the eccentric caused by the drum 29. The worm 49 continuously rotates which in turn rotates the worm gear 50, the normal rotation of which in the drilling of a hole is not sufiicient to bring the pin 7 3 far enough around to engage the end 67 of the catch 68. Should the drill become dull, or strike a very hard spot in the work being drilled, the continued rotation of the. worm gear 50 brings the pin 7 3 under the hooked end 67 of the catch 68 and throws the same inwardly. This continued operation brings the levers 31 and 32 so that the notch 7 2 in the lower end of the lever 31 engages the lug 71 and stops the forward feed of the drill spindle.

In the forward feed of the drill spindle, as heretofore stated, the work holds it back while the spring feeds it forward, the rate being determined by the cutting capacity of the drill. When the drill breaks through the work, the entire pressure is brought upon the friction roll through the eccentric and the spindle is drawn back by the driving of the eccentric by the friction drum.

Upon each revolution of the eccentric, the cam 59 engages the roller 60, carried by the lever 56, and through the link 55, the shaft 52 is rocked, which throws the member 51 forward to disengage the worm gear 50 from the worm 49, so that the spring 61 will return the worm gear to normal position with the pins 7 3 and 74 in engagement, so that the catch 68 will not be thrown to stop the machine and the machine continuously operated, so long as the drill is cutting efliciently.

Instead of having the spring 69, as shown, the spring may be reversed, so that it will engage the catch 68 in rear oftho pivot and thus normally hold the catch so that the lug carried by the same will enter the notch in the lever 31 and stop the forward movement of the drill on each operation and the latch would be tripped by hand.

'From the foregoing description, it will beseen that there has been provided a spring fed drill spindle, in which the drill spindle is prevented from having a rapid forward movement when cutting rapidly, and also prevents the drill spindle from breaking through the work rapidly and injuring the drill. It also provides for means for stop ping the feed of thedrill when not efiiciently cutting as well as means for returning the drill spindle when the drill breaks through the work.

lVhile I'have shown as a special element for regulating the feed, the eccentric 30, it will be understood, of course, that by the term eccentric I mean any cam element which will accomplish the same function, and in the claims, where I have used theterm eccentric, it will beunderstood I mean cam'or eccentric, or any suitable cam mechanism.

1 Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

1, A drilling machine comprising a. rotating drill spindle, yielding means for feeding the same forward, and automatic means eontrolled by the rotation of the drill spindle for regulating the maximum feed of said spindle.

2-. A drilling machine comprising a rotary drill spindle, yielding means for feeding the same forward, and a continuously operated automatic means controlled by the rotation of the drill spindle for regulating the maximum feed of said spindle forward.

3. A drilling machine comprising a rotary drill spindle, spring means for feeding the drill spindle forward, means for regulating the maximum feed of said spindle, and automatic means for stopping the feed of the spindle after it has been rotating a predetermined time when the drill is not cutting efficiently.

4. A drilling machine comprising a rotating drill spindle, yielding means for feeding the same forward, and automatic means 0011- resistance to maintain a consistent or normal feed, and'automatic means for stopping thefeed of the spindle after it has been rotating a predetermined time when the drill is not cutting efficiently.

6. A drilling machine comprising a rotating drill spindle, yielding means for feeding the same forward, and means controlled by the rotation of the drill spindle for preventing'a rapid forward movement of the drill spindle when the drill breaks through the work being operatedupon.

7. A drilling machine comprising a rotary drill spindle, yielding means for feeding the same forward, and an eccentric controlled by the rotation of the drill spindle for maintaining a uniform maximum feeding of. the drill spindle when the character of thejwork being operated upon does not offer suflicient resistance to maintain ,a consistent or normal feed.

1 '8. A drilling machine comprising a rotary drill spindle, yielding means for feeding the same forward, and aneccentric controlled by the rotation of the drill spindle for maintaining a uniform maximum feeding thereof whenthe character of the work being operated upon does not offer sufficient resistance to maintain a consistent or normal feed. r

9. .A drilling machine comprising a rotary drill spindle, yielding mea-nsfor feeding the same forward, means for rotating the drill spindle, a rotary drum driven by the said spindle rotating means, and an eccentric con trolled by the rotation of the drill spindle and driven by the drum for maintaining a uniform maximum feeding of the drill spindle when the character of the work being op; erated upon does not offer suflicient resistance to maintain a consistent or normal feed and to automatically return the drill spindle to the starting point against the tension of the yielding means; a

10. A drilling machine comprising a base, an intermediately pivoted lever carried by the base, a rotary drill spindle longitudinally movable in said base and pivotally connected to the upper end of said lever, spring means connected to the. lower, end of the lever for feeding the drill spindle forward, an eccentric rotatably carried by the lower end of the lever, and a driven drum for ro tating the eccentric for maintaining a uniform maximum feeding of the drill spindle when the character of the work being operated upon does not offer sufficient resist ance to maintain a consistent or normal feed.

11. A drilling machine comprising a base, an intermediately pivoted lever carried by the base, a rotary drill spindle longitudinally movable in said base and pivotally connected to the upper end of said lever, spring means connected to the lower end of the lever for feeding the drill spindle forward, and a driven eccentric carried by the lever and adapted to maintain a uniform maximum feeding of the drill spindle when the character of the work being operated upon does not offer sufficient resistance to maintain a consistent or normal feed.

12. A drilling machine comprising a base, a rotary drill spindle longitudinally movable in said base, spring means for feeding the drill spindle forward, intermediately pivoted spaced levers carried by the base, means for adjustably securing the upper end of the levers to the drill spindle, an eccentric rotatably mounted between the lower end of the levers, and means for rotating said eccentric for maintaining a uniform forward maximum feed of the drill spindle.

13. A drilling machine comprising a base, an intermediately pivoted lever carried by the base, a rotary drill spindle longitudinally movable in said base, and pivotally connected to the upper end of said lever, spring means connected to the lower end of the lever for feeding the drill spindle forward, means for preventing a rapid forward movement of the upper end of the le ver, and means operated by the drum for stopping the feed of the drill spindle after it has returned to the starting point when the drill spindle has been rotating for a predetermined time without effectively cutting.

14:. A drilling machine comprising a base, a rotary drill spindle longitudinally movable in said base, intermediately pivoted spaced levers having their upper end pivotally connected to the drill spindle, spring means for drawing the lower end of the levers rearwardly for feeding the drill spindle for ward, an eccentric pivotally mounted be tween the lower end of the levers, and means engaging the periphery of the eccentric for operating the same, whereby the feed of the drill spindle is regulated by the rim speed of the eccentric.

15. A drilling machine comprising a base, a rotary drill spindle longitudinally movable in said base, an intermediately pivoted lever having its upper end connected to the drill spindle, a spring connected to the lower end of the lever. for drawing the same rearwardly for feeding. the drill forward, an eccentric pivotally mounted in the lower end of said lever, a rotary drum for rotating the eccentric for regulating the feed of the drill forward and to cause rearward movement of the drill spindle after it has completed its cutting operation.

16. A drilling machine comprising a base, a rotary drill spindle longitudinally movable in said base, a pivoted lever connected at one end to the drill spindle, a spring connected tothe lever for causing a forward feed of the drill spindle, an eccentric piv otally mounted in said lever, and a rotary drum engaging said eccentric for regulating the forward feed of the drill spindle and to cause the rearward movement thereof against the tension of the spring.

17. A drilling machine comprising a base, a rotary drill spindle longitudinally movable in said base, a pivoted lever connected at one end to the drill spindle, a spring connected to the lever for causing a forward feed of the drill spindle, an eccentric pivot ally mounted in said lever, a rotary drum engaging said eccentric for regulating the forward feed of the drill spindle, means operated by the drum for stopping the feed of the drill spindle after it has returned to the starting point when the drill spindle has been rotating for a predetermined time without effectively cutting.

18. A drilling machine comprising a base, a rotary drill spindle longitudinally movable in said base, a pivoted lever connected at one end to the drill spindle, a spring connected to the lever for causing a forward feed of the drill spindle, means carried by the lever for regulating the forward feed of the drill spindle, and means for stopping the forward feed of the drill spindle after the same has been rotating for a predetermined time.

19. A drilling machine comprising a base, a rotary drill spindle longitudinally movable in the base, a pivoted lever connected at one end to the drill spindle, a spring connected to the lever for causing a forward movement of the drill spindle, an eccentric rotatably carried by the lever, a rotary drum engaging the periphery of the eccentric and rotating the same for regulating the forward feed of the drill spindle, and means operated by the drum for locking the lever to prevent the feed of the drill spindle after the drill spindle has been rotating a predetermined time.

20. A drilling machine comprising a base, a- .rotary drill spindle longitudinally movable in the base, yielding means for feeding the same forward, an eccentric controlled by the rotation of the drill spindle for regulating the forward maximum feed of the drill spindle, and means for rotating said eccentric for allowing the drill spindle to feed forward and to return the same after it has completed its operation.

21. A drilling machine comprising a base,

a rotary drill spindle longitudinally movable in the base, spring means for feeding the drill spindle forward, an eccentric for regulating the forward feed of the drill spindle, means for rotating said eccentric for allowing the drill spindle to feed forward and to return the same after it has completed its operation, and means operated by the rotating means for stopping the feed of the drill spindle after the drill spindle has been rotating a predetermined time.

22. A drilling machine comprising a base, a rotary drill spindle longitudinally movable in said base, spring means for feeding the drill spindle forward, means for allowing the drill spindle'to feed forward at a predetermined maximum speed and to return the same to its starting point after each operation, and automatic means for stopping the feed of the drill spindle after the same has been rotating a predetermined time.

23. A drilling machine comprising a base, a rotary drill spindlelongitudinally movable in said base, spring means for feeding the drill spindle forward, means for allowing the drill spindle to feed forward at a predetermined maximum speed, and to return the same after the drill has completed its operation, automatic means for stopping the feed of the drill spindle after the same has been rotating a predetermined time without completing its operation, and means for throwing the automatic means out of operation during each normal operation of the drill spindle when the same is effectively cutting.

24;. A drilling machine comprising a base, a rotary drill spindle longitudinally movable therein, spring means for feeding the drill spindle forward, a rotary eccentric for allowing the drill spindle to feed forward under the partial tension of the spring, a

rotating drum driving sald eccentric, a

worm carried by a shaft carrying the drum, a worm gear meshing with the worm, means operated by the worm gear for stopping the feed of the drill spindle after the same has beenrotating a predetermined time without completing its operation, and means operated by the eccentric for throwing the worm gear out of mesh with the worm upon every normal rotation of vthe eccentric, whereby the stopping mechanism will not be operated during the normal operation of the drill.

25. A drilling machine comprising a base, a rotary drill spindle longitudinally movable therein, a lever pivoted to the frame, means foradjustably connecting the lever to the drill spindle, spring means connected to the lever for feeding the drill spindle forward, an eccentric rotatably supported by the lever, a rotary drum engaging the eccentric and driving the same for allowing the spring to feed the drill spindle forward, automatic means operated by the drum for stopping the lever for'preventing the feed of the drill spindle when the same has been rotating apredetermined time without completing its operation, and means operated by the eccentric for throwing the automatic means out of operation during each normal rotation of the eccentric whereby the feed of the drill spindle will not be stopped.

26. A drilling machine comprising abase, a rotary drill spindle longitudinally movable therein, a lever intermediatelyrpivoted to the frame and having its upper end connected to the drill spindle, a spring connected to the lower end of the lever for feeding the drill spindle forward, an eccentric rotatably carried by the lower end of the lever, a rotary drum engaging the periphery of the eccentric, and driven from the drill spindle for regulating the feed of the same, a worm carried by the drum, a worm gear meshing with the worm, means operated by the worm gear for locking the lever against movement when the drill spindle has been rotating for a predetermined length of time, and means operated by the eccentric for throwing the worm gear out of mesh with the worm during each normal, rotation of the eccentric, whereby the feed of the drill spindle will not be stopped.

27. A drilling machine comprising abase, a rotary drill spindle longitudinally movable therein, an elongated pulley carried by the drill spindle, a belt for rotating said pulley, an arm pivotally'and rotatably mounted with the pulley, a block adj ustably connected to the arm by a set screw, a lever intermediately pivoted to the base, means for adjust ably connecting the upper end of the lever to the block, an eccentric pivotally sup ported by the lower end'of the lever, a rotary drum engaging said eccentric, a worm gear carried by one end of the drum shaft a shaft carried by the frame parallel with the drill spindle, a worm carried by the shaft and meshing with the worm gear, a pulley carried by the shaft, a crossed belt passing around the pulley and the elongated drive pulley of the drill spindle, a worm carried by the opposite end of the drum shaft, a worm gear meshing with the worm, means operated by the continued rotation of the worm gear for locking the lever to prevent the forward feed ofthe drill spindle after the drill has rotated a predetermined time suflicient to complete the drilling operation, and means operated by the eccentric for throwing the worm gear out of mesh with the worm during each normal rotation of the eccentric, whereby the feed ofv the drill spindle will not be stopped.

28. A drilling machine comprising a base, a rotary drill spindle longitudinally movable therein, a lever pivoted to the frame and having its upper end pivotally connected to the drill spindle, a spring connected to the lower end of the lever for feeding the drill spindle forward, an eccentric rotatably carried by the lower end of the lever, a. rotary drum driving said eccentric for allowing the spring to feed the drill spindle forward and preventing a rapid forward movement thereof when the drill breaks through and return the drill to the starting point against the tension of the spring, a worm carried by the drum shaft, a rock shaft in the base below the worm, an arm carried by one end of the shaft, a worm gear rotatably carried by the upper end of the arm and meshing with the worm, a coil spring having one end connected to the arm and the opposite end to the worm gear, a pin carried by a sleeve formed in the lower face of the worm gear, an intermediately weighted catch having an outwardly turned end normally spring held in engagement with the sleeve, and having a lug adapted to catch in a notch in the lever when the same has been forced inwardly by contact with the pin, an upwardly extending arm carried by the other end of the rock shaft, and a cam carried by the eccentric for rocking the arm to throw the Worm gear out of mesh with the worm and allow the spring to return the Worm to its normal position during each rotation of the eccentric.

29. A drilling machine comprising a base, a rotary drill spindle longitudinally movable in said base, spring means for feeding the drill spindle forward, a pivoted lever carried by the base, and connected to the drill spindle, an eccentric rotatably carried by the lever, and means for rotating said eccentric for maintaining a uniform for ward maximum feed of the drill spindle.

30. A drilling machine comprising a base, a rotary drill spindle longitudinally movable in said base, spring means for feeding the drill spindle forward, an intermediately pivoted lever carried by the base, means for adjustably connecting the upper end of the lever to the drill spindle, an eccentric rotatably supported by the lower end of the lever, and means for rotating saideccentric for maintaining a uniform forward maximum feed of the drill spindle.

In testimony whereof, I afiix my signature in the presence of two witnesses.

EDXVARD J OSLIN KINGSBURY.

\Vitnesses S. M. BOARDMAN, L. G. LIroHrmLD. 

